This invention relates to a magnetic disk cartridge rotatably housing a magnetic disk therein, and also to a mechanism for opening and closing a shutter mounted on the magnetic disk cartridge.
There has heretofore been proposed a magnetic disk cartridge in which a hard disk (that is, a magnetic disk comprising a rigid substrate having a magnetic layer formed on each of the opposite sides or faces thereof) is rotatably housed in a cartridge casing, and the cartridge casing, containing the hard disk therein, is loaded or inserted into a disk drive unit so that information can be recorded in, reproduced from and erased from the hard disk.
FIGS. 6 to 8 show one such conventional magnetic disk cartridge. FIG. 6 is a perspective view of the magnetic disk cartridge as seen from an upper side thereof, FIG. 7 is a perspective view of the magnetic disk cartridge as seen from a lower side thereof, and FIG. 8 is a perspective view of a main portion of a shutter opening-closing mechanism of the magnetic disk cartridge.
As shown in FIGS. 6 and 7, this conventional disk cartridge includes a box-like cartridge casing 3 formed by joining together upper and lower halves 1 and 2 (made of a rigid plastic or the like) of a shallow dish-shape, a head shutter 5 openably covering a head insertion opening 4 formed in a front face of the cartridge casing 3, a hard disk 6 rotatably mounted in a space defined by the cartridge casing 3 and the head shutter 5.
A spindle insertion opening 7 of a circular shape is formed through a substantially-central portion of the lower half 2, and a center hub 8, provided on a central portion of the hard disk 6, is exposed to the exterior through the spindle insertion opening 7. Reference numeral and symbol 8a denotes a center hole formed in a central portion of the center hub 8. The head shutter 5 is made of rigid plastics etc. as used for the upper and lower halves 1 and 2, and is in the form of a rectangular plate having a sufficient size to cover the head insertion opening 4. The head shutter 5 has a pair of coaxial support shafts 9a and 9b mounted respectively at opposite ends thereof, as shown in FIG. 8. An operating projection 10 is formed on and projects forward from the head shutter 5, the operating projection 10 being disposed above the support shaft 9a. The support shafts 9a and 9b are fitted respectively in bearing holes (not shown), formed in the peripheral face of the head insertion opening 4, with the operating projection 10 directed outwardly, thereby making the head shutter 5 pivotal on the front face of the cartridge casing 3.
This magnetic disk cartridge is loaded or inserted into a disk drive unit so that information can be recorded in, reproduced from and erased from the hard disk 6. More specifically, when the magnetic disk cartridge is inserted into the disk drive unit (not shown) through a medium insertion port, formed in the disk drive unit, with the front face or edge of the cartridge casing 3 (on which the head shutter 5 is mounted) directed forward, a shutter opening member 11, provided within the disk drive unit, engages the operating projection 10 (formed on the front surface of the head shutter 5) before the magnetic disk cartridge reaches an insertion completion position, as shown in FIG. 8A. In this condition, when the magnetic disk cartridge is further inserted, the head shutter 5 is pivotally moved about the support shafts 9a and 9b by this inserting force, so that the head insertion opening 4 is opened. Then, when the magnetic disk cartridge is further inserted into the insertion completion position, the head insertion opening 4 is fully opened as shown in FIG. 8B, and head devices (not shown) are inserted through this insertion opening 4, and are disposed respectively on the opposite sides of the hard disk 6.
At the time when the magnetic disk cartridge is inserted into the insertion completion position, a turntable of the disk drive unit, having a spindle and a magnet for magnetic clamping purposes, is inserted into the cartridge casing 3 through the spindle insertion opening 7, and as a result a distal end portion of the spindle is inserted into the center hole 8a, thereby centering the hard disk 6, and also the lower surface of the center hub 8 is magnetically held or clamped on the upper surface of the turntable. As a result, the hard disk 6 can be driven for rotation, and also the information recording operation and other operations can be effected by the head devices.
A flying or floating magnetic head device is used for this type of magnetic disk cartridge. In the floating magnetic head device, a magnetic head is caused to fly or float a very short distance of a few or several tens of nm (nanometer) off the surface of the hard disk 6 by an air pressure, produced by the rotating hard disk 6, so as to effect the recording of information and so on. When a foreign matter such as dust deposits on the surface of the hard disk 6, the magnetic head may crash, so that the magnetic head and the hard disk are liable to be destroyed. Therefore, the magnetic disk cartridge, which effects the recording etc. of information by the use of the floating magnetic head device, is particularly required to have a high dust prevention effect.
However, as described above, in the conventional magnetic disk cartridge, there is not provided any shutter for covering the spindle insertion opening 7, and therefore foreign matters such as dust are liable to intrude into the cartridge casing 3 through a gap between the peripheral edge of the spindle insertion opening 7 and the center hub 8, so that the magnetic head is liable to crash.
Additionally, foreign matter is liable to deposit on the surface of the center hub 8, and therefore when the magnetic disk cartridge is loaded into the disk drive unit, the foreign matter is liable to be sandwiched between the center hub 8 and the turntable, and as a result the hard disk 6, when driven for rotation, shakes or vibrates. This adversely affects the flying or floating stability of the magnetic head and the reliability of the recording and reproducing operations.
If, in addition to the shutter for the head insertion opening 4, another shutter is provided on the spindle insertion opening 7, the above disadvantages will be overcome. However, if such separate shutters are provided respectively for the head insertion opening and the spindle insertion opening, and are opened and closed independently of each other, there are encountered further disadvantages that the shutter opening-closing mechanism becomes complicated, and that the disk drive unit becomes bulky in size, and becomes costly. Therefore, it is desired to develop a type of shutter construction which will not make the shutter opening-closing mechanism complicated.